Caffeine — how much is too much? | MayoClinic.com

If you rely on caffeine to wake you up and keep you going, you aren’t alone. Caffeine stimulates the central nervous system, alleviating fatigue, increasing wakefulness, and improving concentration and focus.

When to consider cutting back

For most healthy adults, moderate doses of caffeine — 200 to 300 milligrams (mg), or about two to four cups of brewed coffee a day — aren’t harmful. But some circumstances may warrant limiting or even ending your caffeine routine. Read on to see if any of these apply to you